Table Of Contentlibrary
OOtORAW SCHOOL OF 3HIEBS
ootSH. Colorado
PRESSURE LACKING
OF
SEDIMENTARY C0PPE1 ORE IN PLACE
BY
PARKE 0. TNQST
ProQuest Number: 10781445
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A thesis submitted to the Faculty and the Board of Trustees of the
Colorado School of Mines in partial fulfillment of the requirements for
the degree of Master of Science.
Signed!
Golden, Colorado Parke 0. Y:
Date ^ ------1951
Approved!
Golden, Colorado Clifton W. Livingston
Date <2^ 1951
ABSTRACT
This paper on ”Pressure Leaching of Sedimentary Copper Ore in
Place” deals with the preliminary investigations of the possibility of
leaching low grade sedimentary copper ores without mining. The work
covers the indicated recovery that can be expected with certain types
of reagents. Many of the problems, both technical and economic, are
covered briefly.
The results of these preliminary investigations are summarised
and presented in graph form.
TABLE OF CONTENTS
Page
Acknowledgments 1
Introduction 2
General 3
Preliminary Investigations 5
Petrography 5
Crushing and Sizing 6
Permeability of the Ore 6
Permeability of Cement Mixtures 9
Leaching Tests 13
Ammonium Hydroxide Leaching 13
Sulfuric Acid Leaching lh
Sodium Bicarbonate Leaching 16
Chemical Analysis 16
Results 20
Conclusions 3U
Bibliography 35
ILLUSTRATIONS
Page
Figure 1 Physical Arrangement of Lab Equipment 8
Figure 2 Permeability of Cement Mixtures 12
Figure 3 Graph for Colorimetric Assay of Solutions 19
Figure h Sample Calculations 21
Figure 5 Recovery vs Time Graph 23
Figure 6 Recovery vs Time Graph 2k
Figure 7 Recovery vs Time Graph 25
Figure 8 Recovery vs Quantity of Leaching Solution Graph 2?
Figure 9 Recovery vs Quantity of Leaching Solution Graph 28
Figure 10 Recovery vs Quantity of Leaching Solution Graph 29
Figure 11 Recovery vs Tlme-Quantity Graph 30
Figure 12 Recovery vs Tlme-Quantity Graph 31
Figure 13 Recovery vs Time-Quantity Graph 32
Figure lU Recovery vs Time-Quantity Graph 33
1
ACKNOWLEDGMENTS
I wish to acknowledge the kind assistance of Mr. Charles W. Starks,
Instructor, of the Chemistry Department, in granting me the use of his
laboratory for chemical analysis; of Dr. Warren E. Wagner, Professor,of
the Department of Geology, for his assistance and permission to use the
equipment of the Pétrographie Laboratory in the study and identification
of the mineral constituents of the ore tested; of Professor C. W.
Livingston, of the Department of Mining, for his suggestions and
criticisms.
2
INTRODUCTION
The consumption of large quantities of our national reserve of
copper during two costly wars has brought the United States very close
to the "have not" position with respect to this metal. It was this
situation and our knowledge of large deposits of low grade sedimentary
copper ore, too low in grade to be mined by conventional methods, that
prompted this investigation of pressure leaching of these ore bodies
in place.
It is not intended to prove in this paper that copper in small
quantities in sedimentary rocks can be leached at a profit. This
report will show that the ore which was used in these experiments can
be leached in place. There are many factors involved in the economic
problem. The investigation of these various factors will be left to
future investigators.
3
GENERAL
The problem of pressure leaching of an ore in place is quite
complicated. It involves a study of the* principle minerals and cement
ing agents in the host rock. Subsurface geological methods must be
used to determine the thickness, extent, and attitude of the mineralized
beds. Core drilling is necessary to determine changes in the mineral
content from one location of the deposit to another, and also changes
in the permeability from one portion of the deposit to another.
The economics of the problem involves sampling and ore estimation.
Chemical consumption, regeneration of leaching solutions, wash solutions,
and the precipitation of the recovered metal, must all be investigated
thoroughly. Large size drill holes must be put down to the mineralized
beds for the injection of barren solution and pumping of the pregnant
solution. Large amounts of chemicals will be involved. Special types
of equipment will be required. There will be considerable lag between
the beginning of operations and the time when returns start coming in.
All of these factors are important in the economics of the problem. The
total capital investment will probably be comparatively small for a
project of this type, but the time lag will be large. This lag will
increase the interest-bearing period on the capital investment.
Each deposit will have its own peculiar characteristics and there
fore will require extensive research and preliminary investigation.
h
Each deposit, because of its own peculiar characteristics will call for
a different plant layout. Some deposits will contain very little, if
any, calcium carbonate whereas others will contain sufficient to preclude
the use of acid as a leaching agent. Each deposit will have certain
characteristics inherent in its location which will affect such items as
the strength of solutions , and the amount of wash solutions.
These various aspects of the problem of pressure leaching will not
be covered in this report, and are mentioned at this time only to point
out the many individual problems involved and the large amount of
research that will be required for each and every deposit before oper
ations can be started.
The material given in this report is based on the test work per
formed on one specific ore. This ore, donated by Professor Livingston
of the Mining Department, was from the Wingate sandstone beds of Utah
in an area typical of the Colorado Plateau Region, A number of similar
deposits occur in the Dakota sandstone beds and the Permian Red Beds.
The ore minerals are the same for all the deposits, but the Permian
Red Beds contain a larger percentage of iron oxide than do those of
the Wingate and Dakota sandstones.
